Some properties of the hierarchical model reproducing the stress state of the epicentral area of the 2003 Chuya earthquake

Abstract

The stress state of the Earth’s crust in the region of the Chuya earthquake of 2003 (Gorny Altay) is studied using the data of long-term epicentral observations by dense networks of temporary stations. These data comprise 545 seismic events, which widely vary in energies and whose parameters are determined highly accurately. Two hierarchical levels of the stress field are revealed and their spatial structure and temporal behavior are investigated. It is shown that the subregional stress field, which is determined from the data on strong earthquakes, is predominantly stable across the studied area, where the regime of horizontal shear with submeridional orientation of principal pressure axes is observed. The local stress field calculated from the weak seismic events experiences regular variations, which are consistent with the block structure of the crust; this field is heightand time-dependent.